JPH1167675A - High-speed rotary vapor phase thin-film forming device and high-speed rotary vapor phase thin-film forming method using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-speed rotary vapor phase thin film forming device with few occurrences of pollutant by means of uniformly controlling reaction gas flow applied to CVD of the manufacture process of a semiconductor wafer substrate and an epitaxial process, in which high quality is demanded, and to form a thin film whose film thickness is uniform, whose interface characteristic is uniform, and crystal defect is few with CVD and epitaxy through the use of the device. SOLUTION: This device is provided with a rotary substrate holding body 12, where plural reaction gas supply ports 16 are installed at the top of a hollow reaction furnace 10, exhaust ports 15 at the base and a wafer substrate 11 inside and with a rectifying board 17 where plural holes are pierced on an internally upper part. The device supplies reaction gas inside and its vapor phase-grows the thin film on the surface of the wafer substrate 11 on the rotary substrate holding body 12. In such a case, the hollow inner part is divided into upper/ lower parts, whose equivalent inner diameters differ. The upper equivalent inner diameter is smaller than the lower equivalent inner diameter, a lower end B of the upper part and an upper end U of the lower part are connected by the connection part of a prescribed form and the hollow inner part continues. The lower end U (the upper end of the lower part) of the connection part is arranged in a position having a prescribed height difference with the surface of the wafer substrate 11 loaded on the rotary substrate holding body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed rotary vapor phase thin film forming apparatus and a high-speed rotary vapor phase thin film forming method using the same, and more particularly, to a CVD or epitaxial process in a semiconductor wafer substrate manufacturing process requiring high quality. A high-speed rotating vapor-phase thin film forming apparatus with less contaminant generation by uniformly controlling the reaction gas flow applied to the wafer, and a crystal defect having a uniform film thickness and uniform in-plane characteristics by CVD or epitaxial using the apparatus. The present invention relates to a method for forming a high-speed rotating vapor-phase thin film for forming a thin film having less heat.

[0002]

2. Description of the Related Art FIG. 5 is a schematic explanatory view showing an example of a conventional vapor phase thin film forming apparatus. In FIG. 5, a rotating substrate holder 52 for mounting a wafer substrate 51 such as a silicon wafer, a rotating shaft 53 for rotating the rotating substrate holder 52, and a heating A heater (not shown) for driving the rotation is connected to the rotating shaft 53. The periphery of the rotating mechanism such as the rotating substrate holder is surrounded and protected by a partition plate 58. A plurality of exhaust ports 55 for exhausting unreacted gas and the like are provided at the bottom of the reaction furnace 50, and are connected to an exhaust control device (not shown). On the other hand, a plurality of gas supply pipes 56 for supplying a raw material gas and a carrier gas into the furnace and a disc-shaped current plate 57
And a number of holes 57a for regulating the gas flow are formed in the current plate 57. The conventional vapor phase thin film forming apparatus is configured as described above, and the substrate 51 placed on the rotating substrate holder 52, which rotates at a predetermined rotation speed by the rotation of the motor, is rotated at a predetermined temperature by the heater 54 while rotating. Heated. At the same time, a reaction gas such as a source gas and a carrier gas is supplied into the reaction furnace 50 by a plurality of gas supply pipes 56,
Introduced via 56 to equalize gas momentum and pressure distribution,
Next, the gas is passed through a number of holes 57a of the current plate 57 so that the gas flow rate distribution in the reaction furnace becomes uniform,
The reaction gas is uniformly supplied to the wafer substrate 51 on the substrate 2 to vapor-grow the thin film.

In the vapor phase thin film forming apparatus for forming a thin film on a semiconductor wafer as described above, it is necessary to prevent the generation of particles due to the thin film forming gas and the deposition of deposits on the inner wall of the reactor. Various proposals have been made to prevent the occurrence of crystal defects due to the inconvenience described above and to obtain a thin film-formed wafer having a uniform thin film and a uniform film thickness. For example, in Japanese Patent Application Laid-Open No. Hei 5-74719, the crystal flow is prevented by preventing the temperature change in the reaction furnace by controlling the supply flow rate of the raw material gas to a predetermined value. In Japanese Patent Application Laid-Open No. 5-90167, the amount of source gas, the pressure in the furnace, the number of rotations of the rotating substrate holder, and the like are controlled to a predetermined value so as to make the in-plane temperature distribution of the wafer substrate uniform during thin film formation, thereby preventing slip. I'm trying. In Japanese Patent Application Laid-Open No. 6-216045, a shielding tube is provided on a part of the inner wall of the reactor where precipitates are liable to be formed, while keeping the inner peripheral surface smooth, and the reactor is easily cleaned after performing a thin film forming operation. In addition, the gas flow is maintained in a laminar state to form a uniform thin film. In Japanese Patent Application Laid-Open No. 7-50260, the method of introducing a raw material gas and a carrier gas into a reaction furnace is set to a predetermined value so that the gas momentum and the gas pressure are made uniform and the raw material gas and the like are deposited on the substrate at a uniform flow rate. It is supplied to make the thickness of the thin film uniform.

[0004]

However, even in the conventional vapor phase thin film forming apparatuses proposed in the above-mentioned various proposals, it is possible to sufficiently prevent crystal defects from occurring on the wafer substrate on which the thin film has been grown, and inconveniences such as particle adhesion. However, in particular, with the recent high integration of semiconductors, the quality of wafer substrates has been required to be higher and higher. Is also often a problem. The present invention has been made in view of the deterioration of the quality of a wafer substrate in the formation of a vapor-phase grown thin film using such a conventional vapor-phase thin film forming apparatus, and has been made for the purpose of solving them. The inventors first studied in detail the phenomenon occurring in the conventional vapor phase thin film forming apparatus. As a result, a phenomenon was observed in which a large amount of particles adhered to the reactor wall, which necessitated a reduction in the maintenance cycle, and the particles adhered to the reactor wall adhered to the wafer substrate, causing crystal defects. It has been found that these particles directly cause deterioration of the wafer quality as particles that become discolored or adhered.

From the above findings, the inventors have further attempted to find the cause of the phenomenon of large amount of particles adhering to the reactor wall.
The raw material gas flow in the reactor was studied. As a result, it has been further clarified that the following phenomenon occurs in the reactor. That is, the reaction gas such as the silicon source gas introduced from the top of the reaction furnace and supplied onto the wafer substrate 51 at a uniform flow rate as described above is heated by the heater 54 and becomes lower in the temperature in the lower part of the reaction furnace 50 than in the upper part. Reaches the vicinity of the wafer substrate 51 and is heated. As a result, as schematically shown by arrows in FIG. 5, a rising gas flow is generated, a rising phenomenon of the reaction gas is caused along the reactor wall, and a gas vortex is generated. In addition, since the heated reaction gas rises, the temperature in the entire region of the reaction furnace 50 also rises, so that uniform nucleation of the raw material gas for forming a thin film in the gas phase increases, and particle generation in the gas phase increases. I do. Further, when the gas vortex is generated, the dopant in the reaction gas may be re-introduced at the outer peripheral portion of the wafer substrate 51 on the rotating substrate holder 52, and the in-plane resistance value distribution of the obtained wafer substrate may not be uniform. It also causes uniformity. Furthermore, the rising phenomenon of the reactant gas flowing down to the vicinity of the wafer substrate to the upper part of the reactor is generated separately from the generation of the gas vortex, on the outer peripheral side of the rotary substrate holder-52, by the so-called "roughness of gas flow". Turbulence, which results in a complicated flow. When the gas flow becomes rough, the unreacted gas to be discharged from the exhaust port 55 reacts and deposits a thin film component on the outer peripheral surface of the rotating substrate holder 52 or faces the outer peripheral surface of the rotating substrate holder 52. Particles may adhere to the reactor wall.

Since the state of gas flow in the reactor is an important factor in forming a homogeneous gas phase thin film, the above-mentioned vortex generation phenomenon has been studied in more detail.
That is, it became clear that a vortex is generated on the upper outside of the rotating substrate holder 52 as shown in a comparative example described later. In this case, if the gas flow rate in the axial direction of the rotating substrate holder is increased to an extremely high speed of about 1 m / s or more and the gas flow rate is increased, the gas flow becomes laminar, and the gas vortex flow causing various inconveniences described above. The generation of rough gas flow can be suppressed to some extent. However, for this purpose, a large amount of carrier gas needs to be flowed, which increases the size of the vapor phase thin film forming apparatus, increases equipment costs, and increases running costs. In addition, it can be suppressed by reducing the gas pressure in the exhaust part. That is, according to the ideal gas law, the pressure and volume of the gas change in inverse proportion. Therefore, decreasing the furnace pressure has the same effect as increasing the volume, and increases the flow velocity (linear velocity) at the gas inlet. According to the laws of motion of hydrodynamics, the effect of pressure drop is the same as the effect of increasing flow rate if the effect of pressure on the viscosity of the gas fluid can be neglected. Range of pressure used in actual epitaxial, 10
At ~ 200 Torr, the change in gas viscosity is considered to be small, so that the furnace pressure of 40 Torr and the gas flow state of 200 liter / min are set to the furnace pressure of 20 Torr, 100 Torr / min.
It is the same as the gas flow state of liter / min. However, in this case, it is difficult to control the gas pressure in the low pressure section.

Furthermore, in order to suppress the generation of the gas vortex, the diameter of the upper part of the reactor is narrowed to be smaller than that of the lower part, and an attempt is made to prevent the generation of the gas vortex by closing the space where the high temperature reaction gas rises. Was. However, in this case, it is possible to prevent particles from adhering to the upper part of the reactor and the like, but FIG. 8 is a schematic explanatory view of a vapor phase thin film forming apparatus in which the diameter of the upper part of the reactor used in the comparative example described below is simply reduced. For example, as shown by an arrow, it has been found that a gas vortex or a rough gas flow occurs at an enlarged portion of the reactor diameter located outside the rotary substrate holder. If this gas vortex or gas flow becomes rough in the area where the diameter increases, the reactor also causes problems such as particles adhering to the lower peripheral wall of the reactor and deposition of thin film components due to the reaction of unreacted gas. It has also been clarified that inconveniences such as shortening of the maintenance cycle also occur when only the area is changed.

[0008] Based on the above findings, the inventors have found that the above-mentioned inconveniences such as the deterioration of the quality of the thin-layer-formed wafer substrate and the shortening of the maintenance cycle of the reactor are caused by the gas flow of the upward flow of the gas in the reactor. In addition to finding that it is in turbulence, not only does the upper space part where the inconvenience of the gas flow occurs is occluded or closed, but also a curved connection part at a predetermined position between the upper and lower parts of the reactor with different diameters By providing a predetermined ratio of the upper diameter, the lower diameter of the reaction furnace, and the diameter of the rotating substrate holder, the outer peripheral surface of the reactor wall or the rotating substrate holder in the lower part of the conventional gas phase thin film forming apparatus described above. The present invention has been found that it is possible to prevent a large amount of particles from adhering to the film, to deposit a thin film component, and to prevent dopant from being taken in at the outer peripheral portion of the wafer, thereby preventing deterioration in the quality of the wafer substrate. That is, the present invention provides a vapor phase thin film growth apparatus that prevents particles generated by uniform nucleation of silicon source gas from adhering on the peripheral wall of the reaction furnace and preventing deposition of thin film components on the outer periphery of the rotating substrate holder and the inner peripheral wall of the furnace. The present invention also provides a method for vapor-phase growing a high-quality and uniform thin film on a wafer substrate with few defects.

[0009]

According to the present invention, a plurality of reactant gas supply ports are provided at the top of a hollow reactor, and an exhaust port is provided at a bottom thereof.
A rotating substrate holder on which a wafer substrate is placed, and a rectifying plate having a plurality of holes formed in an upper portion of the inside, and a reaction gas is supplied to the inside of the rotating substrate holder to cover the surface of the wafer substrate on the rotating substrate holder. In a vapor phase thin film forming apparatus for vapor-phase growing a thin film, the hollow interior of the reactor is divided into cylindrical upper and lower portions having the same central axis and different equivalent inner diameters, the upper equivalent diameter is smaller than the lower equivalent inner diameter, Further, the upper lower end and the lower upper end are connected by a connecting portion, the hollow interior is continuous, and the lower end of the connecting portion (lower upper end) is a predetermined height difference from the surface of the wafer substrate mounted on the rotating substrate holder. And a high-speed rotating vapor-phase thin film forming apparatus provided at a position having the following.

[0010] In high speed vapor film forming apparatus of the present invention, a hollow internal horizontal cross-section a circular reactor, wherein the rotating substrate holder is a circular outer diameter (D _S), the inner diameter of the reactor upper (D ₁₎ is at 90 to 110% of the outer diameter (D _S),
In addition, the inner diameter (D ₂ ) of the lower part of the reactor is one of the outer diameter (D _S ).
The connecting portion is set to satisfy the following condition A, and the height difference between the upper end of the lower part of the reactor and the surface of the wafer substrate placed on the rotating substrate holder is determined by the outer diameter (D
It is preferably within 4% of _S ). Here, the condition A means that a half of the difference between the inner diameter of the upper part (D ₁ ) and the inner diameter of the lower part (D ₂ ) on a cross section taken along a plane passing through the central axis of the upper and lower cylindrical parts of the reactor is W. In any given cross section, (1) the upper and lower ends are one more than the lower and upper ends.
/ 2W-W is located above in the range, (2) the connecting portion is a line segment connecting the upper lower end and the lower upper end, and a line segment extending from the lower upper end portion to the inside of the 1 / 2W furnace perpendicular to the central axis. And 1 toward the upper and lower ends with a radius of 1/2 W, one end of which is in contact with the line segment.
/ 4 arc and a line segment from the other end of the arc to the upper and lower ends (a region indicated by oblique lines in FIG. 10), and is substantially convex inside the furnace. It is configured to have a shape.

Further, according to the present invention, in the high-speed rotating vapor-phase thin-film forming apparatus, the rotating speed of the rotating substrate holder is set to 5 or less.
A high-speed rotating vapor-phase thin-film formation, characterized in that a reaction gas comprising a thin-film forming raw material gas and a carrier gas is supplied from a plurality of reaction gas supply ports at a speed of not less than 00 rpm, and is passed through a hole of a rectifying plate and circulated on a wafer substrate. A method is provided.

The vapor phase thin film growth apparatus of the present invention is configured as described above, and suppresses generation of a gas vortex caused by a reaction gas rising phenomenon generated along a reaction furnace wall in a conventional vapor phase thin film growth apparatus. It can be suppressed by changing the furnace shape to make it smaller than the lower diameter to eliminate the generation space, and at the same time, it can prevent the rise of the gas phase temperature in the upper part of the reactor, so the uniform nucleus of the raw material gas for thin film formation such as silicon Generation is suppressed and particles generated in the gas phase are reduced. Therefore, it is possible to prevent a maintenance cycle from being shortened due to the particles adhering to the reaction furnace wall, and to prevent crystal defects due to the particles adhering to the wafer and deterioration in the quality of the wafer. Further, the generation of the gas vortex is suppressed uniformly without obstructing the flow of the gas just above the wafer placed on the rotating substrate holder from flowing from the center of the wafer to the outer periphery in parallel with the wafer surface. Therefore, a high-quality thin-layer-formed wafer substrate having a uniform in-plane resistance value distribution can be obtained without re-uptake of the dopant in the gas phase at the outer peripheral portion of the substrate.
Furthermore, since the upper part of the reactor is made thinner, the gas flow velocity in the axial direction of the rotating substrate holder can be increased with a relatively small amount of carrier gas, and the amount of carrier gas is reduced as compared with the conventional apparatus.

In addition, since the upper and lower ends of the small diameter and the upper end of the large diameter of the reactor are connected to each other by providing a connecting portion satisfying predetermined conditions, the gas flow can be made smooth and the diameter can be enlarged. Is gradually increased, the gas flow from the center to the outer periphery generated on the rotating substrate holder is rectified, and the diameter of the outer periphery of the rotating substrate holder is increased by making the reactor upper diameter smaller than the lower portion. So-called rough gas flow can be suppressed. As a result, it is possible to prevent particles from adhering to the inner wall of the enlarged diameter connecting portion or the lower part of the reactor and the deposition of thin film forming components. Further, since the ratio of the upper diameter of the reactor, the lower diameter of the reactor, and the diameter of the rotating substrate holder is set to a predetermined value, it is possible to prevent the upward flow of gas in the reactor to reduce the generation of particles, and to reduce gas vortex and gas flow. This makes it possible to prevent the occurrence of roughening, and also to prevent particles adhering to the furnace wall from falling onto the wafer substrate on the rotating substrate holder.

Further, the wafer substrate surface on the rotating substrate holder and the lower end of the connecting portion (upper end of the lower part of the reaction furnace) have a predetermined difference in height with respect to the outer diameter of the rotating substrate holder. Does not hinder a smooth gas flow, and can prevent the upward flow of the gas, and can prevent the generation of the gas vortex and the rough gas flow. Therefore, it is possible to obtain a high quality thin film formation wafer substrate without crystal defects.
In addition, the method for forming a high-speed rotary vapor phase thin film of the present invention uses the above-described apparatus, and in particular, controls the rotation speed of the rotating substrate holder to uniformly and uniformly react the reactant gas flow on the rotating substrate holder in a laminar flow. Since it can be supplied, similarly, a high-quality thin film having no crystal defects can be vapor-phase-formed on a wafer substrate.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited by the following examples. FIG. 1 is a schematic sectional explanatory view of one embodiment of a vapor phase thin film growth apparatus of the present invention. In FIG. 1, a reactor 10 is divided into a cylindrical upper part 1 having the same central axis and a cylindrical lower part 2 having the same central axis.
Are formed thinner than the lower part 2. That is, the upper inner diameter D ₁ is D ₁ <D ₂ smaller than the lower inner diameter D _2. The upper end U of the large-diameter lower part 2 and the lower end B of the small-diameter upper part 1 are connected by a connecting part 19, and the inner middle space of the reactor is continuous though the upper and lower parts have different diameters. In this case, as shown by a two-dot chain line (imaginary line) in FIG. 1, a small-diameter upper part 1 and a connecting part 19 are lined with a liner wall inside a hollow formed in the same manner as a conventional reaction furnace having upper and lower parts having the same diameter. It may be installed as. In addition, the side wall surface of the upper portion 1 of the reactor is usually formed parallel to and perpendicular to the side wall surface of the lower portion 2, and is perpendicular to the upper surface of the rotating substrate holder.
The connecting portion 19 between the upper lower end B and the lower upper end U is formed in a convex shape, so that the gas flow in the inner peripheral surface area of the upper part 1 of the reactor is smoothly guided to the inner peripheral surface area of the lower part 2.

In FIG. 1, a lower portion 2 of a large-diameter reactor
A rotating substrate holder 12 on which a wafer substrate 11 is placed is rotatably supported by a rotating shaft 13 and disposed below the rotating substrate holder 12 and a wafer substrate 11 placed thereon. Is provided. The rotating substrate holder 12 is provided on the wafer substrate 1 placed on the upper surface thereof.
1 and the lower end of the connecting portion 19 are disposed below so as to have a predetermined height difference (H). A motor (not shown) for driving the rotation is connected to the rotation shaft 13, and the periphery of these rotation mechanisms is surrounded by a partition plate 18 and protected from reaction gas and the like. Further, a plurality of exhaust ports 15 for exhausting unreacted gas and the like are provided at the bottom of the reactor 10. On the other hand, a plurality of reaction gas supply ports 16, 16 are disposed on the top of the upper part 1 of the reaction furnace.
₄ ) Raw material gas such as dichlorosilane (SiH ₂ Cl ₂ ), hydrogen (H ₂ ), helium (He), argon (A
A reaction gas of a carrier gas such as r) is supplied.

The diameter D ₁ of the upper 1 of the reactor, the diameter D _S of the large diameter D ₂ and rotating the substrate holder 12 of the lower 2 is preferably in the following relationship. (1) D ₁ is larger than the diameter of the wafer substrate 11 placed on the rotating substrate holder 12. If D ₁ is smaller than the wafer diameter, particles that have fallen off from the inner wall surface of the furnace upper part 1 tend to adhere to the wafer substrate,
As a result, crystal defects measured as LPD (wafer surface laser scatterer (including particles)) increase. Further, it is usually difficult to measure the non-contact temperature of the outer peripheral portion of the wafer substrate using infrared rays in the vapor phase thin film growth step. _{(2) D 1 = 0.9D S} ~1.1D S
(D ₁ / D _S ratio is 0.9 to 1.1) and D ₂ ≧ 1.25
It is preferable to have a ratio relationship of D _S (D ₂ / D _S ratio is 1.25 or more). When the D ₁ / D _S ratio is smaller than 0.9,
Although there is a relationship with the height difference H of the connecting portion, the wall surface of the upper portion 1 is too close to the wafer substrate 11 mounted on the rotating substrate holder 12, and particles dropped from the furnace inner wall surface are likely to adhere to the wafer substrate. . Therefore, because the above-mentioned D ₁ is as if smaller than the wafer substrate diameter, the quality of the increased crystal defects measured as LPD film formed wafer substrate is reduced. On the other hand, if the D ₁ / D _S ratio is larger than 1.1, the gas flow rises along the inner wall of the reaction furnace, causing inconvenience such as generation of a gas vortex. If the D ₂ / D _S ratio is smaller than 1.25, the gas flow on the outside of the rotating substrate holder 12 cannot be suppressed from being rough, so that particles may adhere to the inner wall of the reactor facing the outside of the rotating substrate holder 12. This is because the unreacted gas enters below the rotating substrate holder 12 and reacts to deposit a thin film forming component on the inner wall of the reactor lower part 2. (3) Further, the ratio of D ₂ / D ₁ is 1.2 or more (D ₂ / D ₁ ≧ 1.2), and D ₁ and D ₁
1/2 of the reactor top and bottom diameter difference of ₂ (D ₂ -D _1/2) or more, i.e., as gap distance W of the inner peripheral wall and the inner wall of the upper 1 of the lower 2 is 0.1 D ₁ or more I do. D ₂ / D ₁ ratio is smaller than 1.2, i.e., when W is narrower than 0.1 D _1, Mai up phenomenon of upward gas flow the gas vortex flow is generated occurs along the reactor wall, the reactor This is because the upper diameter is made thinner to prevent the gas rising phenomenon and the effect of suppressing the generation of the gas vortex is reduced.

The connecting portion 19 of the reactor is 1 / (1/1) of the difference between the upper inner diameter (D ₁ ) and the lower inner diameter (D ₂ ) on a cross section taken along a plane passing through the central axis of the upper and lower cylindrical portions of the reactor.
Assuming that 2 is W, the upper lower end B is located above the lower upper end U in a range of 1 / 2W to W in any arbitrary cross section. If this distance is smaller than 1/2 W, the flow of gas discharged from the rotating substrate holder 12 is obstructed due to the relationship with H described later, which causes turbulence. If the distance is larger than W, the distance between the connecting portion and the outer peripheral portion of the holding body 12 relatively increases, so that a low-pressure region is formed immediately below the connecting portion, and the discharge from the holding body 12 is performed. This creates a flow that is opposite to the flow of the generated gas, causing turbulence. In the present invention, the lower end of the upper portion of the reactor refers to a portion where the upper cylindrical portion ends, that is, a portion immediately before the expansion by the connecting portion is started. However, if the diameter expansion ratio is less than about 10% (diameter expansion amount / height) and is considered to be substantially a cylinder, that portion is also included. Similarly, the upper end of the lower part of the reactor also includes a portion whose diameter reduction ratio is less than about 10%. Further, the connecting portion includes a line segment connecting the upper lower end B and the lower upper end U, a line segment extending from the lower upper end portion to the inside of the 1/2 W furnace perpendicular to the central axis, and a radius 1 / It is substantially present in a region surrounded by a 1/4 arc toward the upper and lower ends of the 2W and a line segment connecting the other end of the arc to the upper and lower ends (region indicated by oblique lines in FIG. 10) and substantially. It is configured so as to have a convex shape inside the furnace. FIG. 10A shows a region where the connecting portion 19 of the present invention exists by a shaded portion. FIGS. 10B to 10E show specific examples of the connecting portion. If the shape of the connecting portion deviates from this range, a portion having a low pressure will be generated and turbulence will occur. In particular, it is not preferable that the gas flow from the rotating body is disturbed from the lower side of the arc portion and the lower side of the line segment extending from the upper end of the lower portion to the furnace inside in relation to H described later. The phrase that the connecting portion 19 is substantially within this range means that the connecting portion 19 slightly deviates from this region near the upper lower end or the lower upper end (each less than 5% of the length of the connecting portion), and each end of the connecting portion 5% It has been confirmed that at least 90% of the effect of the present invention can be obtained if 90% of the central portion excluding the above falls within this range, and it is substantially within the range where the effect of the present invention can be obtained. Also,
Substantially convex means that it is convex in the furnace over at least the majority of the connecting portion including the upper and lower ends,
It is also within the scope of the present invention that only the vicinity of the portion connected to the upper end of the lower portion of the connecting portion is formed as a concave portion for the purpose of further rectifying effect. In this case, only the concave portion may deviate from the above-described region.

The upper surface of the rotary substrate holder 12 is such that the surface of the wafer substrate 11 placed on the holder 12 is below the upper end U of the lower part of the reactor and has a predetermined height difference H from the upper end U. Placed in The height difference H is preferably within a distance of 4% of the diameter (D _S ) of the holder 12, that is, within 0.04D _S. If the upper surface of the wafer substrate 11 is below the upper end U, the flow of the gas discharged from the surface of the holder 12 is undesirably hindered. Further, when the height difference H exceeds 0.04D _S, becomes a the distance between the holding member 12 the outer peripheral portion and the connecting portion forms a low pressure area at the junction just below portion will be relatively increased retention It creates a flow that opposes the gas flow exhausted from the body 12 and causes turbulence. The lower limit of H is determined by the transition layer of the gas flow supplied to the upper part of the rotating substrate holder 12, that is, the gas flow such as the source gas supplied through the rectifying plate 17 as shown by the arrow in FIG. The thickness is set to be larger than the thickness (T) of the gas layer having a vector from the center to the outer peripheral portion on the rotating substrate holder 12. When the height difference H is smaller than the transition layer thickness T, the gas flow from the center of the wafer substrate 11 on the rotary substrate holder 12 to the outer peripheral portion is hindered by the lower end B of the upper portion 1 of the reactor, and the gas flows along the inner wall of the reactor. This is because a rising phenomenon occurs to promote the generation of a gas vortex, so that a large amount of precipitates are formed on the connecting portion 19 and the inner wall of the lower portion 2 of the reactor.

The transition layer thickness T of the gas flow on the rotary substrate holder 12 (that is, on the wafer substrate 11) is mainly the value of the atmospheric gas in the reaction furnace in a conventional reaction furnace. It varies according to the type, the pressure in the reactor, and the number of rotations of the rotating substrate holder, but can be calculated by the following equation (1). Equation (1) below is generally expressed in hydrodynamics. T = 3.22 (ν / ω) ^1/2 (1) (where ν is the kinematic viscosity coefficient of the reaction gas in the reactor (mm ² /
s) and ω represents the angular velocity of rotation (rad / s). In this case, ω takes the minimum value during the operation of forming a thin film in the vapor phase thin film growth apparatus. For example, the source gas is a silane gas, the carrier gas is a hydrogen gas, and the rotation speed of the rotating substrate holder is 500 to 2000 rpm (52 to 2 rpm).
09 rad / s), the transition layer thickness T is about 5 to 5
0 mm. Therefore, it is preferable to dispose the upper surface of the rotary substrate holder at a height difference larger than the T value from the lower end B of the upper portion 1 of the small diameter reactor. This allows
The gas flow from the center to the outer periphery of the wafer substrate is smooth, and no particles of the thin film forming material adhere to the inner wall of the furnace, and the obtained thin film forming wafer has no defects in the crystal phase and a uniform thin film is formed.

As described above, in the vapor phase thin film growth apparatus of the present invention, the reactor is a continuous hollow cylindrical body having different diameters divided into upper and lower portions, and upper and lower portions having different diameters are formed by predetermined connecting portions. Except for connection and continuous connection, it can be designed and manufactured in substantially the same manner as the above-described conventional reactor having a hollow cylindrical body having the same diameter as the vapor phase thin film growth apparatus. Further, a vapor phase growth method using the vapor phase thin film growth apparatus of the present invention can be performed in the same manner as the conventional method. For example, in the vapor phase thin film growth apparatus of the present invention configured as described above, the inside of the reaction furnace 10 is evacuated by the exhaust control device connected to the exhaust ports 15, 15, and the pressure in the furnace is reduced to, for example, the source gas or It is adjusted to 20 to 50 torr with a reactive gas of a carrier gas. On the other hand, the rotating substrate holder 12 and the placed wafer substrate 11 are simultaneously rotated by the rotation of the rotating shaft 13 by operating the motor. The wafer substrate 11 on the rotating substrate holder 12 is heated to, for example, about 900 to 1200 ° C. by the heater 14, and at the same time, while controlling the flow rate from the plurality of reaction gas supply ports 16, the raw material gas and A reaction gas composed of a carrier gas is supplied into the reaction furnace 10. The gas flow supplied from the plurality of reaction gas supply ports 16, 16 to the space S has a uniform momentum and pressure distribution.
By passing the gas through 7a, the gas flow rate in the reaction furnace is made uniform and supplied onto the substrate, whereby the thin film can be uniformly vapor-grown on the substrate.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments. However, the present invention is not limited by the following examples. Example 1, Comparative Examples 1 and 2 Like the reaction furnace shown in FIG.
The reactor inner diameter D ₁ , lower inner diameter D ₂ , and rotating substrate holder diameter D _S have the diameters shown in Table 1, respectively, and the height difference H between the lower end of the connecting portion and the upper surface of the rotating substrate holder 12 is shown in Table 1. 1, the connecting portion 19 is an arc having the shape shown in FIG. 10 (e), and the radius of curvature r and the width W thereof are designed as shown in Table 1, respectively. An apparatus for forming a vapor phase thin film of a reactor was formed. Using each of the vapor phase thin film forming apparatuses formed as described above, the rotating substrate holder 12 is used.
With the rotation speed of 2,000 rpm, a hydrogen carrier gas at a flow rate of 30 liter / min (standard condition, the same applies hereinafter) was passed at a furnace pressure of 40 Torr, and the gas flow state was analyzed using the finite element method. FIGS. 2 to 4 show gas flow diagrams in the radial direction of the reactor as a result of the analysis.

As is apparent from FIGS.
In FIG. 2, it can be seen that the gas flow above the rotating substrate holder 52 is substantially laminar, and no vortex is generated below the connecting portion 19. In Comparative Example 1 (FIG. 3) in which the height difference H was increased as compared with Example 1, a gas vortex occurred below the connecting portion. Compared with the first embodiment, the gas swirl is generated below the connecting portion also in the comparative example 2 (FIG. 4) in which the upper portion has a small diameter. Further, under the conditions shown in Table 1, S
iH ₄ gas is 0.3 liter / minute, and diborane (B ₂ H ₆ ) is 0.1 ppm in H ₂ gas as a dopant.
Table 1 shows the contained gas at 0.01 liter / min.
The hydrogen gas (carrier gas) flow rate described in (1) above was supplied, and a B ₂ H ₆ dopant silicon thin film was vapor-phase grown on an 8-inch φ silicon wafer substrate placed on the rotating substrate holder 12. After the vapor-phase growth thin film was formed, the adhesion of particles to the connection part of the vapor-phase growth apparatus used and the inner peripheral wall of the lower part of the reactor were visually observed. In addition, the number of LPDs (wafer surface laser scatterers) of 0.135 μm or more was measured for the properties of the crystal phase on the obtained thin film-formed wafer substrate surface using a Surfscan 6200 manufactured by Tencor Corporation, and the number per wafer was measured. . The thickness of the formed thin film was measured by an infrared interference thickness meter, and the maximum thickness (F
_max ) and the minimum thickness (F _min ) are determined, and the uniformity of the thin film thickness is calculated as (F _max −F _min ) / (F _max + F _min ) × 100.
It was calculated as Further, the resistance value of the obtained thin film-formed wafer substrate was measured by using the CV method, and the maximum value (R _max ) was obtained.
And the minimum value (R _min ) is determined, and the uniformity of the resistance value due to the incorporation of the dopant is determined by (R _max -R _min ) / (R _max + R
_min ) × 100. These results are also shown in Table 1. This result also indicates that the thin film formed on the wafer substrate using the reactor of Example 1 has a uniform thickness and uniform characteristics such as in-plane resistance.

Comparative Examples 3 and 4 In a conventional reactor constructed substantially in the same manner as the apparatus shown in FIG. 5, hydrogen gas as a carrier gas was passed in the same manner as in Example 1, and the gas flow state was similarly changed. Analyzed (Comparative Example 3). As a result, the gas flow diagram in the radial direction of the reactor obtained by the analysis is shown in FIG. In FIG. 6, the laminar flow state of the gas flow above the rotary substrate holder 52 is also disturbed, and a large vortex is generated on the upper outside. In a reactor under the same conditions,
Except for increasing the hydrogen gas flow to 200 l / min,
The gas flow state was analyzed in the same manner as in Comparative Example 3 (Comparative Example 4). As a result, the gas flow diagram in the radial direction of the reactor obtained by the analysis is shown in FIG. In FIG. 7, the gas flow above the rotating substrate holder 52 is in a laminar flow state, and a large vortex has also disappeared in the upper part on the outside. Comparative Example 3 and Example 4
In the same manner as described above, a thin film was vapor-grown, and the characteristics of the film were examined. The results are also shown in Table 1.

COMPARATIVE EXAMPLE 5 As shown in FIG. 8, a gas-phase thin-film growth apparatus in which the upper inner diameter is made smaller and the upper and lower diameters are made different from each other in the same manner as in Example 1, Flow analysis was performed.
The reactor 80 of FIG. 8 has a small-diameter upper part 1 ′ and a large-diameter lower part 2 ′.
Although the inner diameters of the upper and lower portions are different, the lower and upper ends of the upper and lower portions are located on substantially the same horizontal plane without a difference in height, and are connected by a substantially horizontal flat connecting portion 89. It is configured similarly to the reaction furnace of the vapor phase thin film growth apparatus. The same members as those in the apparatus shown in FIG. 1 are indicated by the same numeral of the first digit or by the same reference numeral. In reactor 80, the reactor upper inner diameter D _1, the lower inner diameter D ₂
And rotating the substrate holder diameter D _S shown in Table 1. Hydrogen gas was circulated in the reaction furnace 80 as in Example 1, and the gas flow state was analyzed. As a result, FIG. 9 shows a gas flow diagram in the radial direction of the reactor obtained by the analysis. FIG.
In this case, the laminar flow state of the gas flow above the rotating substrate holder 52 was disturbed, and a large vortex flow was generated on the upper outside. In Comparative Example 5, a thin film was vapor-grown in the same manner as in Example 1, and the characteristics of the film were examined. The results are also shown in Table 1.

[0026]

[Table 1]

As is clear from the above Examples and Comparative Examples, the inside of the reactor is made smaller with upper and lower parts having different diameters.
By dividing and providing a height difference at each end and connecting at a predetermined connection portion, the gas flow above the rotating substrate holder is made laminar without increasing the gas flow rate, that is, the gas flow rate. You can see that. Further, it can be seen that the vortex generated in the upper portion outside the rotating substrate holder of the conventional reactor having the same diameter in the reactor becomes small, and the vortex can be eliminated by setting the length ratio of the upper and lower portions to a predetermined value. . For this reason, in the reaction furnace of the embodiment of the present invention, the gas flow supplied from the upper straightening plate flows down in a laminar flow state on the rotating substrate holder without turbulence or roughening, and the gas flow supplied on the mounted wafer substrate This shows that a thin film having a uniform thickness and uniform in-plane characteristics is formed.

[0028]

According to the present invention, there is provided a high-speed rotating vapor-phase thin film forming apparatus,
The reaction gas flow can be stably supplied in a laminar flow state onto the surface of the wafer substrate placed on the rotating substrate holder by connecting the upper and lower portions having different inner diameters constituting the reaction furnace with a curved connection portion. Further, the fluid flows in the radial direction of the rotating substrate holder, and turbulence such as eddy currents is generated on the outer peripheral surface side, so that the fluid can flow smoothly without being roughened and flow out from the exhaust port.
Therefore, without increasing the gas flow rate, at a relatively small gas flow rate, and within the range of the furnace pressure that can be accurately controlled, it is possible to realize a smooth, uniform and smooth flow state without disturbance of the reaction gas, A thin film having a uniform thickness and uniform in-plane characteristics can be formed at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing an example of the outline of a reactor structure of a high-speed rotating vapor-phase thin film forming apparatus of the present invention.

FIG. 2 is a gas flow diagram showing an analysis result of a gas flow in a reactor in Example 1 of the present invention.

FIG. 3 is a gas flow diagram showing an analysis result of a gas flow in a reactor in Comparative Example 1 of the present invention.

FIG. 4 is a gas flow diagram showing an analysis result of a gas flow in a reactor in Comparative Example 2 of the present invention.

FIG. 5 is an explanatory cross-sectional view showing an example of the outline of a reaction furnace structure of a conventional high-speed rotating vapor-phase thin film forming apparatus.

FIG. 6 is a gas flow diagram showing the result of gas flow analysis of Comparative Example 3 using a conventional reactor.

FIG. 7 is a gas flow diagram showing a gas flow analysis result of Comparative Example 4 in which the gas flow rate was increased using a conventional reactor.

FIG. 8 is an explanatory cross-sectional view showing an example of an outline of a conventional reactor structure having upper and lower portions having different inner diameters.

FIG. 9 is a gas flow diagram showing a result of gas flow analysis of Comparative Example 5 using a conventional reactor.

FIG. 10 is a cross-sectional explanatory view showing the structure of a connecting portion and an existing region according to the present invention;

[Explanation of symbols]

10, 50, 80 Reactor 11, 51, 81 Wafer substrate 12, 52, 82 Rotating substrate holder 13, 53, 83 Rotating shaft 14, 54, 84 Heater 15, 55, 85 Exhaust port 16, 56, 86 Gas supply Mouth 17, 57, 87 Rectifying plate 17a, 57a, 87a Rectifying hole 18, 58, 88 Rotating mechanism partition plate 19, 89 Connecting part 1, 1 'Reactor upper part 2, 2' Reactor lower part B Upper lower end U Lower upper end D ₁ Inner diameter of upper part of reactor D ₂ Inner diameter of lower part of reactor D _S Diameter of rotating substrate holder H Height difference between lower end of connecting part and upper surface of rotating substrate holder WW = (D ₁ −D ₂ ) / 2

Continued on the front page (72) Inventor Tadashi Ohashi 30 Soya, Hadano-shi, Kanagawa Prefecture, Toshiba Ceramics Co., Ltd. (72) Inventor Katsuhiro Chaki 30 Soya, Hadano-shi, Kanagawa Prefecture, Toshiba Ceramics Co., Ltd. (72) Inventor Tatsuo Fujii Inside Tokuyama City, Tokuyama City, Yamaguchi Prefecture Eguchi Kaisaku 8231-5 Tokuyama Toshiba Ceramics Co., Ltd. (72) Inventor Katsuyuki Iwata Tokuyama City, Tokuyama City, Yamaguchi Prefecture Eiji Kaisaku 8231-5 Tokuyama Toshiba Ceramics Co., Ltd. (72) Inventor Shinichi Mitani 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Office (72) Inventor Yasuaki Honda 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Office (72) Inventor Yusuke Sato 1 Toshiba-cho, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Inside Toshiba R & D Center

Claims (3)

[Claims] 1. A hollow reaction furnace having a plurality of reaction gas supply ports at the top, an exhaust port at the bottom, a rotating substrate holder on which a wafer substrate is placed, and a plurality of holes at the top inside. In a vapor phase thin film forming apparatus having a current plate and supplying a reaction gas to the inside to vapor-grow a thin film on the surface of a wafer substrate on a rotating substrate holder, the hollow interior of the reaction furnace has the same central axis. The equivalent inner diameter is divided into cylindrical upper and lower portions, the upper equivalent inner diameter is smaller than the lower equivalent inner diameter, the upper lower end and the lower upper end are connected by a connecting portion, and the hollow interior is continuous, and the connecting portion lower end ( A high-speed rotary vapor phase thin film forming apparatus, wherein a lower upper end is disposed at a position having a predetermined height difference from a surface of the wafer substrate mounted on the rotary substrate holder. 2. The reactor has a hollow internal horizontal cross section having a circular cross section, the rotating substrate holder having a circular shape having an outer diameter (D _S ), and an inner diameter (D ₁ ) at an upper portion of the reaction furnace having an outer diameter (D ₁ ). 90 to 110% of D _S ), and the inner diameter (D
₂ ) is 125% or more of the outer diameter (D _S ), and the connecting portion is set so as to satisfy the following condition A, and is placed on the upper end of the lower part of the reactor and on the rotating substrate holder. The difference in height (H) from the surface of the wafer substrate is 4 times the outer diameter (D _S ).
%. Condition A: When the difference between the inner diameter of the upper part (D ₁ ) and the inner diameter of the lower part (D ₂ ) on the cross section of a plane passing through the central axis of the upper and lower cylindrical parts of the reactor is W, In any arbitrary cross section, (1) the upper and lower ends are located above the lower and upper ends within a range of 1/2 W to W, and (2) the connecting portion is a line connecting the upper and lower ends and the lower and upper ends. A line segment extending from the upper end portion to the inside of the 1/2 W furnace perpendicular to the center axis, a quarter arc having a radius of 1/2 W, which is in contact with the line segment at an upper end toward the lower end, and an upper end extending from the other end of the arc; Being substantially present in a region surrounded by a line connecting the lower end and being configured to have a substantially convex shape inside the furnace. 3. The high-speed rotating gas-phase thin film forming apparatus according to claim 1, wherein the rotation speed of the rotating substrate holder is set to 500 rpm or more, and the thin film forming raw material gas and the carrier gas are supplied from the plurality of reaction gas supply ports. A high-speed rotating vapor-phase thin film forming method, comprising supplying a reactant gas through the holes of the rectifying plate and flowing the reactant gas over the wafer substrate.